Linux Pocket Guide

Name

kill [options] [process_ids] — bash

Synopsis

shell built-in stdin stdout - file -- opt --help --version

The kill command sends a signal to a process. This can terminate a process (the default), interrupt it, suspend it, crash it, and so on. You must own the process, or be the superuser, to affect it.

$ kill 13243

If this does not work—some programs catch this signal without terminating—add the -KILL option:

$ kill -KILL 13243

which is virtually guaranteed to work. However, this is not a clean exit for the program, which may leave resources allocated (or other inconsistencies) upon its death.

If you don’t know the PID of a process, try the pidof command:

$ /sbin/pidof emacs

or run ps and examine the output.

In addition to the program /bin/kill in the filesystem, most shells have built-in kill commands, but their syntax and behavior differ. However, they all support this usage:

$ kill -N PID
$ kill -NAME PID

where N is a signal number, and NAME is a signal name without its leading “SIG” (e.g., use -HUP to send the SIGHUP signal). To see a complete list of signals transmitted by kill, run kill -l, though its output differs depending which kill you’re running. For descriptions of the signals, run man 7 signal.